How to choose the right prescription for your reading glasses without relying solely on age

After a certain age, reading a label, checking your phone, or threading a needle can start to require more effort. Many people solve this problem with pre-made reading glasses, but before choosing, the inevitable question arises: what prescription do I need?

Reading glasses will have numbers like +1.00, +1.50, +2.00, or +3.00. These values indicate the positive power of the lenses, expressed in diopters. The higher the number, the more the lens helps you focus at close range.

That doesn't mean there's an exact prescription for every age. Two 50-year-olds may need different prescriptions because their distance vision, focusing ability, working distances, and individual prescriptions may not be the same.

Matters offers pre-made lenses from +1.00 to +3.50, as well as a +0.00 option with no magnification. This last option does not correct presbyopia: it is a lens without positive power.

Step 1: Think about what you're going to use them for.

Reading a novel is not the same as working in front of a monitor. The viewing distance affects the comfortable screen brightness.

A book or a phone is usually held closer to the eyes than a desktop computer. A prescription chosen for reading small print may be too intense for viewing a screen at a greater distance.

Before trying on glasses, place the text or device exactly where you would normally use it. Don't move the object closer or farther away to adjust the lenses: the glasses should adjust to your task.

Step 2: Start with the lowest power setting that allows you to read comfortably.

Reading glasses shouldn't force you to hold the text excessively close. Nor should they create a feeling of disproportionate magnification.

As a practical guideline, look for the lowest magnification that allows you to see clearly at your usual viewing distance, without squinting or holding the text further away. Choosing more magnification than necessary doesn't make you see "better"; it reduces the range of distances at which your vision is comfortable.

Step 3: Check both eyes

Pre-made glasses incorporate the same power in both lenses. This works best when both eyes need similar correction and there is no significant astigmatism.

Try looking at the text with both eyes open, then gently cover one eye and then the other, without pressing down. If one eye clearly sees worse, shadows appear, or the letters become distorted, identical glasses for both eyes might not be the right solution.

Eye differences, astigmatism, and other refractive errors require a personalized prescription. The College of Optometrists points out that ready-made glasses always have the same prescription for both eyes and that their one-size-fits-all design doesn't fit everyone perfectly.

Step 4: Value comfort, not just sharpness

During a brief test, a lens can make letters appear very large and sharp. The question is how you feel after several minutes.

An incorrect prescription may be associated with:

• Headache.
• Sensation of pressure around the eyes.
• Need to continually zoom in or out on the text.
• Dizziness.
• Difficulty maintaining focus.
• Obvious difference between both eyes.

Presbyopia usually begins around age 40, but it can also coexist with myopia, hyperopia, or astigmatism. An eye exam determines the specific correction each eye needs.

When is it not advisable to choose solely by trial and error?

Request a check-up if you've never had glasses, if one eye sees worse than the other, if discomfort persists with different prescriptions, or if you also have difficulty seeing at a distance.

Pre-made glasses can be a practical solution for specific tasks when the visual need is simple and fairly symmetrical. Age can give you an idea of when presbyopia might begin, but it shouldn't be used as an automatic prescription guide.